The military services utilize various size trucks, from one quarter ton up to approximately ten ton capacity, for cargo transportation purposes. Commonly the cargo is protected from rain, snow, wind etc. by means of a flexible fabric cover drapped over inverted U-shaped bows spaced along the length of the cargo box. A disadvantage with this system is that when the truck is used to transport military personnel the fabric cover provides no protection against enemy small arms fire or mortar fragments. I propose an add-on system of ballistic armor slats or plates for ballistically protecting personnel seated within the cargo area. In my proposed system the armor slats are located within horizontal fabric pockets or sleeves sewn or otherwise attached to the outer surface of the aforementioned fabric cover. The armor slats are removable and/or replaceable when it becomes necessary to lighten the vehicle for cargo-carrying purposes. Slat replacement is also envisioned as a means for periodically changing the armor material occasioned by materials technology improvements. This system overcomes armor weight penalty problems since the armor is used only when the vehicle has a relatively small load, i.e. humans; when heavy cargo is being transported the armor slats are removed to lighten the vehicle, to thus accommodate the higher payload.